Hong Kong -LRB- CNN -RRB- -- A huge manhunt involving soldiers and police is underway in China for an elusive armed robber who is thought to be behind a string of murders dating back to 2004 .

The search for 42-year-old Zhou Kehua -- one of the country 's most wanted criminals -- is focused on the southwestern city of Chongqing , China 's biggest metropolis , after a woman was shot dead and two others injured on Friday morning outside a bank during an attempted robbery , the state-run Xinhua news agency reported .

Later that day , local police reported that a railway policeman was killed while in pursuit of a man believed to be Zhou -- his tenth victim in eight years following a series of robberies in Chongqing , Nanjing and Changsha .

All his victims were shot in the head , according to media reports , while police say he targeted people withdrawing money from banks .

Chongqing authorities recalled officers on vacation as they launched a full-scale search for the fugitive in mountainous areas around the city , Xinhua said . Police and military units from Hunan and Jiangsu provinces were also mobilized .

The search uncovered a cave that Zhou is believed to have stayed in , China Daily reported . Inside were two cigarette cases , a T-shirt and human waste , the report added . Police have said Zhou is an expert at survival in the wild , though there is no record of him serving in the military .

According to China Daily , the Ministry of Public Security has classified Zhou as a `` class-A '' suspect , with a total 5.4 million yuan -LRB- US$ 849,000 -RRB- in rewards being offered for information leading to his capture .

A huge -- but ultimately fruitless -- search for Zhou was carried out in January this year after he allegedly shot and robbed a man who had just withdrawn 200,000 yuan -LRB- $ 31,700 -RRB- from a bank in Nanjing before fleeing in a car .

Nanjing Public Security Bureau 's Xuanwu district office told CNN at the time that more than 80,000 police officers took part in the manhunt . It also published two video clips online of the suspect escaping the scene .

Authorities have warned people against attempting to confront Zhou as he is considered `` ruthless and highly dangerous , '' Xinhua said .

China increases bounty for deadly robber

China dispatches thousands in hunt for robber

CNN 's Dayu Zhang contributed to this report .

@highlight

Search for Zhou Kehua -- one of China 's most wanted criminals -- focused on city of Chongqing

@highlight

Zhou accused of killing ten people during a series of attempted robberies since 2004

@highlight

42-year old escaped similar manhunt in Nanjing in January after a man was shot during a robbery

@highlight

Zhou classified as a `` class-A '' suspect and public have been warned not to approach him